WG342 IIS6 - Public web servers must use TLS if authentication is required. - 'SSL 3.0 Client'

Information

Transport Layer Security (TLS) is optional for a public web server. However, if authentication is being performed, then the use of the TLS protocol is required.

Without the use of TLS, the authentication data would be transmitted unencrypted and would become vulnerable to disclosure. Using TLS along with DoD PKI certificates for encryption of the authentication data protects the information from being accessed by all parties on the network. To further protect the authentication data, the web server must use a FIPS 140-2 approved TLS version and all non-FIPS-approved SSL versions must be disabled.

FIPS 140-2 approved TLS versions include TLS V1.0 or greater. NIST SP 800-52 specifies the preferred configurations for government systems.

Solution

1. Obtain and install a server certificate from a .mil Certificate Authority or approved DoD ECA.
2. Open the IIS Manager > Right click on the website to be examined > Select properties > select the Directory Security tab > Select the Edit button in the Secure communications section.
3. Select Require secure channel (SSL) and Require 128-bit encryption check boxes.
4. Set the version SSL\TLS by creating and setting the following registry to not allow anything lower than TLS. Ensure the following value exists in each of the keys:

Enabled REG_DWORD 0

HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\PCT 1.0\Client

HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\PCT 1.0\Server

HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 2.0\Client

HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 2.0\Server

HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 3.0\Client

HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 3.0\Server

The keys for TLS 1.0 do not require the Enabled value to be present, but if it is, it needs to be set to REG_DWORD 1, to enable TLS.

See Also

http://iasecontent.disa.mil/stigs/zip/July2015/U_IIS_6-0_V6R16_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-13, CAT|II, Rule-ID|SV-28566r2_rule, STIG-ID|WG342_IIS6, Vuln-ID|V-13694

Plugin: Windows

Control ID: 142bc84be3c4222f15197a5a7dc32f619412a1e164ca927d94bab4c9c2bf2e4d